The lively British history mag/website History Today has a crowd of British historians choosing their favourite (mostly but not necessarily British) histories of 2019.
Update: Helen Webberley from Melbourne Auz endorses one of the recommended titles:
Robert Poole’s Peterloo: an English Uprising (Oxford) was excellent.Her blog post on Peterloo is here
I don’t know if this is the definitive account of Peterloo, because I haven’t read any other, but I do know that the book’s place in my historical thinking about British politics and society will be long-lasting.